The invention relates to a rotational damper with a damper housing which surrounds an electromagnetic damper motor and is fastened to a first mass via a fastening element and with an coupling lever which is supported for pivoting relative to the damper housing and is connected with a second mass, and a strain wave gear mechanism for vibration damping which has a rigid unit having an inner spline and is connected with the damper housing and a flexible unit having an outer spline and is connected with the fastening element, wherein the two units of the strain wave gear mechanism are form fittingly coupled with each other via the splines for transmitting and/or converting a rotational movement, and with an oval wave generator which is rotatably supported in the flexible unit, wherein a rotation of the wave generator causes a deformation of the flexible unit.
An electric damper of the aforementioned type is known from WO 2011/042085 A1 for damping the relative movement between a first and a second mass. The damper includes a strain wave gear mechanism with an oval wave generator which is driven by the mass movement and which is integrated in a transmission, wherein a first transmission element that forms a stator is caused to perform a rotational movement whereby a second transmission element which forms a rotor and is directly or indirectly coupled with the first transmission element is rotated. Either on the first or on the second transmission element means for generating a magnetic field are provided. The strain wave gear mechanism includes a flexible unit with an external spline, a rigid unit with an internal spline meshing with the external spline and the wave generator which is arranged in the of the flexible unit and deforms the flexible unit.
DE 101 37 230 C1 discloses an electrically driven strain wave gear mechanism with a rigid unit which has a spline and a flexible unit which also has a spline, wherein the flexible unit undergoes a dynamic elastic deformation so that the spline of the flexible unit is brought into engagement with the spline of the rigid unit always in separate regions so that the flexible unit moves relative to the rigid unit, wherein the dynamic elastic deformation of the flexible unit is caused by magnetic forces which are influenced by means of electrical currents. The flexible unit has a flux-conducting region, which is configured for conducting magnetic fluxes and for this purpose has sufficient cross sectional surfaces, wherein magnetic fluxes flowing via the flux-conducting region cause magnetic forces which act on the flux-conducting region and with this act directly on the flexible unit.
DE 197 47 566 C1 relates to a piezo-driven strain wave gear mechanism with a rigid unit which has a spline, so called “circular spline”, a flexible unit which also has a spline, so-called flex spline, and an ellipsoid wave generator which dynamically deforms the flexible unit so that the spline of the flexible unit can be brought into engagement with the spline of the rigid unit always in two separate regions so that the flexible unit moves relative to the rigid unit. The wave generator has piezo-actuating elements, which are arranged fixed in position relative to the flexible unit and deform the flexible unit by means of mutually coordinated length changes.
The mentioned state of the art discloses so-called strain wave gear mechanisms in connection with the damping in wheel suspensions of motor vehicles, however there are no sufficient means to limit the maximal deflection of the deflection lever during deflection of the damper, which is undesired in connection with damping devices for motor vehicles.
EP 1 354 731 B1 relates to a damping arrangement for a vehicle suspension, which includes a torsion spring unit and a rotational damper. In order to limit the deflection of a lever arm of the wheel suspension a resilient stop is provided which is connected with the vehicle superstructure. Thus a stop for limiting the movement of the wheel suspension is provided which is independent from the damper, and is thus associated with increased construction costs.
DE 10 117 934 B4 relates to a drive with a motor and a transmission which is arranged downstream of the motor, in particular for motor vehicles with an automatically closable vehicle door. In order to decouple the drive shaft of the transmission a disengageable transmission is used which includes a transmission housing with a cylindrical hollow space in which an epicyclic gear mechanism is rotabably supported, which is provided with a housing and has concentric input and output shafts. The housing of the epicyclic gear mechanism can be rotatively fixed relative to the transmission housing via a braking device, which is actuatable by an actuator. Such a braking device however does not have the reliability required with regard to a rotational damper for a motor vehicle suspension.